What Japanese chef is credited with inventing modern nigiri sushi?

Hanaya Yohei is credited with inventing modern nigiri sushi.

Hanaya Yohei was a Japanese chef and restaurateur in Edo, now Tokyo, during the late Edo period. Around 1824, he is commonly associated with developing nigirizushi: hand-pressed vinegared rice topped with a slice of seafood. His version became known as Edo-style or Tokyo-style sushi.

The dish was practical as well as inventive. Before refrigeration, fish was often lightly cooked, salted, marinated in soy sauce, or treated with vinegar to slow spoilage. Nigiri was also sold as convenient fast food, making it different from the much older fermented forms of sushi.

A common mix-up is confusing Hanaya Yohei with famous modern sushi chefs such as Jiro Ono or Masaharu Morimoto. Those chefs helped refine or popularize sushi, but they are not generally credited with creating modern nigiri. Hanaya's original pieces were also larger and used more heavily seasoned fish than many contemporary examples.